The weight training field includes many machines sold under various names, such as Cybex, that are built to perform various weight training exercises. For example, in a Cybex weight training system, there might be one machine for doing a shoulder press exercise, another machine for doing a triceps press exercise, yet another machine for doing a biceps curl exercise, and so on. Each machine typically includes a stack of weights and a selector comprising an insertable pin that can be inserted beneath a particular weight in the stack. When the exercise is performed, it is performed against a resistance comprising all the weights in the stack that are located above the pin while the weights in the stack below the pin are left behind. By moving the pin to different positions in the stack, the user can adjust or vary the exercise mass.
The above described weight stack and pin structure is often referred to in the weight training art as a selectorized weight stack. The term “selectorized” means there is a selector which the user can manipulate to pick up and use a desired number of weights from the weight stack.
Selectorized dumbbells are known which comprise a set of weights located in two spaced apart stacks of weight plates. The weight plates in each stack can be separate from the weight plates in the other stack so that each weight plate forms a single weight. Alternatively, one weight plate in one stack can be joined to one weight plate in the other stack so that a single weight is formed by the pair of joined weight plates. In either of these designs, the weight plates in each stack are nested against one another with a gap or space being provided between the stacks of weight plates.
The selectorized dumbbell further comprises a handle that can be dropped down between the stacks of weight plates. At least one selector is provided to allow the handle to be coupled to a desired number of weight plates from each stack so that the desired number of weight plates are loaded from each stack onto either end of the handle. The selector can comprise a pin that is inserted beneath a selected weight or a movable selector carried on the handle that is slidable or rotatable relative to the handle to pick up different numbers of weight plates. The selector is manipulated by the user, e.g. by changing the position of the pin or by sliding or rotating the selector, to vary or adjust the amount of weight carried by the handle of the dumbbell.
After a weight adjustment operation is performed by the user, the user can pick up the dumbbell by lifting up on the handle of the dumbbell to lift the handle of the dumbbell, along with all the weight plates attached to either end of the handle, from between the remaining weight plates in each stack. The remaining or non-selected weight plates will simply remain in each stack in whatever stand or rack is provided for their storage. The user can then exercise with the dumbbell in a normal fashion. Following such exercise, the user can replace the handle of the dumbbell and the attached weights by dropping the dumbbell back into the space of gap formed between the remaining weights in the two stacks thereof.
One type of selectorized dumbbell is shown in U.S. Pat. No. 5,637,064 issued to the Applicants hereof. Other types of selectorized dumbbells are shown in U.S. Pat. Nos. 4,529,198, 6,149,558, 6,228,003 and 6,416,446.
Selectorized dumbbells have been manufactured with custom weight plates having a solid, plate-like form. In those selectorized dumbbells where the weight plates in the two stacks are joined together in pairs by connecting members such as side rails, the connecting members are often welded to the weight plates to form the connection. In those selectorized dumbbells where the weight plates in each stack comprise individual weights, it is not necessary to weld or attach pairs of weight plates to each other. Nonetheless, the weight plates again typically have a solid, plate-like form and must be provided with some type of means, such as a cut-out, a recess, a lobe, etc., that cooperates with the selector to allow the weight plate to be picked up and raised by the handle when the selector is positioned to select the weight plate. Thus, selectorized dumbbells when manufactured and shipped by the manufacturer are shipped as a complete unit, weights and all.
It is relatively expensive to ship selectorized dumbbells to a distributor, retailer or purchaser due to the weight of the dumbbell. In addition, shipping costs are expected to increase over time. Thus, there is a need in the art to provide a selectorized dumbbell which would be less costly to ship, but this need is inconsistent with the fact that such dumbbells as known in the art require custom manufactured weight plates as described above.